| Beaver River | |
| Pushpin Map: | Canada Southern Ontario |
| Pushpin Map Caption: | Location of the mouth of the Beaver River in southern Ontario |
| Subdivision Type1: | Country |
| Subdivision Name1: | Canada |
| Subdivision Type2: | Province |
| Subdivision Name2: | Ontario |
| Subdivision Type3: | Region |
| Subdivision Name3: | Central Ontario |
| Subdivision Type4: | Regional Municipality |
| Subdivision Name4: | Durham |
| Discharge1 Location: | Beaverton, Ontario |
| Discharge1 Avg: | 2.833m3/s |
| Source1: | Unnamed pond |
| Source1 Location: | Scugog |
| Source1 Coordinates: | 44.0961°N -79.0775°W |
| Source1 Elevation: | 303m (994feet) |
| Mouth: | Lake Simcoe |
| Mouth Location: | Brock |
| Mouth Coordinates: | 44.4319°N -79.1639°W |
| Mouth Elevation: | 219m (719feet) |
| River System: | Great Lakes Basin |
| Basin Size: | 327.3km2 |
The Beaver River is a river in Durham Region in Central Ontario, Canada.[1] It is part of the Great Lakes Basin, and is a tributary of Lake Simcoe. The river's drainage basin is mostly in Durham Region with the remaining portion in the city of Kawartha Lakes; the entire watershed is under the auspices of the Lake Simcoe Region Conservation Authority.[2]
The river begins at an unnamed pond in Scugog on the Oak Ridges Moraine and heads north, passing briefly through Uxbridge before returning to Scugog. The river continues north and its valley becomes largely marshy, paralleled by the now defunct Toronto and Nipissing Railway line to Coboconk. The river passes under Ontario Highway 12/Ontario Highway 7 and enters Brock. At the community of Cannington, the river turns northwest and reaches its mouth at Lake Simcoe at the community of Beaverton.